My mum used to buy useless gadgets
Including (but not restricted to):

The kebab maker : insert slices of vegetable and meat into a plastic tube then simply push a skewer through them! Differing from making a kebab by hand only in the additional expense and time spent washing it up after.

The device for holding a whole leg of ham for easy carving/slicing: a traditional item this, but of no real use unless you get through an awful lot of ham, say, if you own a butchery or delicatessen, which she didn't.

A vacuum packing machine: in the days before sous vide became trendy this meant we had the 'luxury' of vacuum sealed sandwiches at school. The fillings were still bloody awful (Shippams crab paste, cheese so mild it wouldn't offend the most fundamental of religions etc.) but boy were they fresh!

Devices for cleaning the outside of windows using sponges with powerful magnets in to match ones on the inside of the window: genius apart from the fact that it merely moved the dirt to a different part of the window as it had no squeegee function.

An aerial booster to pick up French TV transmissions: I imagine this was designed to encourage us kids to speak French but really, French TV is atrociously bad, except for Canal+ which of course was a subscription channel anyway and certainly would not have helped with my linguistic skills as the opportunities for using the phrases "My what a big tool you have!" and "Excuse me while I bend over" are fairly limited.
( number5 has been fighting tramps and losing., Mon 3 Oct 2011, 18:02, Reply)